Downhole tool for measuring a fluid flow rate therethrough and a well completion incorporating same

ABSTRACT

A downhole tool includes a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter, and a first turbine disposed in the first diameter of the housing. The downhole tool further includes means for measuring a rotational velocity of the first turbine, a second turbine disposed in the second diameter of the housing, and means for measuring a rotational velocity of the second turbine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application 61/029,606, filed Feb. 19, 2008, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tool for measuring fluid flow, particularly gas flow, in wireline operations conducted in downhole environments.

2. Description of Related Art

It is often desirable to measure the flow rate of fluids flowing through a conduit. Orifice plate flow meters, mass turbine flow meters, or volumetric turbine flow meters disposed in line with conduits are commonly used to measure flow rates of fluids flowing through the conduit. Such conventional flow meters, however, are not designed to measure fluids exhibiting a wide range of flow rates, and are therefore unable to differentiate the flow contributions of separate formation perforations downhole to the total flow. Accordingly, using such conventional flow meters in downhole environments that exhibit widely varying flow rates results in multiple trips into the downhole environment to capture the necessary information.

While downhole tools for measuring fluid flow rate exist, considerable shortcomings remain.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a downhole tool is provided. The downhole tool includes a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter, and a first turbine disposed in the first diameter of the housing. The downhole tool further includes means for measuring a rotational velocity of the first turbine, a second turbine disposed in the second diameter of the housing, and means for measuring a rotational velocity of the second turbine.

In another aspect a downhole tool is provided. The downhole tool includes a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter, a first bracket disposed in the passageway and affixed to the housing within the first diameter, and a first shaft coupled with the first bracket. The downhole tool further includes a first turbine coupled with the first shaft, a second bracket disposed in the passageway and affixed to the housing within the second diameter, and a second shaft coupled with the second bracket. The downhole tool further includes a second turbine coupled with the second shaft, means for measuring a rotational velocity of the first turbine, and means for measuring a rotational velocity of the second turbine. The first turbine and the second turbine rotate about a common axis.

In yet another aspect, a well completion is provided. The well completion includes a well extending to a productive zone, a wellhead, and a downhole tool disposed in the well proximate the productive zone. The downhole tool includes a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter, a first turbine disposed in the first diameter of the housing, and means for measuring a rotational velocity of the first turbine. The downhole tool further includes a second turbine disposed in the second diameter of the housing, and means for measuring a rotational velocity of the second turbine. The well completion further comprises one of a production string and a wireline disposed in the well and extending between and in fluid communication with the downhole tool and the wellhead.

The present invention provides significant advantages, including the capability of measuring both low fluid flow rates and high fluid flow rates with a single downhole tool, and excellent resolution at very low gas densities and downhole pressures.

Additional objectives, features and advantages will be apparent in the written description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, wherein:

FIG. 1 is a side, elevational view of an illustrative embodiment of a downhole tool for measuring flow rates of fluids flowing therethrough;

FIG. 2 is a top, plan view of the downhole tool of FIG. 1;

FIG. 3 is a cross-sectional view of the downhole tool of FIG. 1, taken along the line 3-3 in FIG. 1;

FIG. 4 is a cross-sectional view of the downhole tool of FIG. 1, taken along the line 4-4 in FIG. 2;

FIGS. 5 and 6 are enlarged, cross-sectional views, corresponding to the view of FIG. 4, of portions of the downhole tool of FIG. 1, as indicated in FIG. 4;

FIGS. 7 and 8 are, cross-sectional views, corresponding to the view of FIG. 5, of the portion of the downhole tool shown in FIG. 5 illustrating exemplary embodiments of a means for determining a rotational velocity of a first turbine of the downhole tool; and

FIGS. 9 and 10 are stylized, partial cross-sectional views of illustrative embodiments of a well completion incorporating the downhole tool of FIG. 1.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The present invention represents a downhole tool useful in measuring the flow rate of fluids in a downhole well environment. The tool is particularly useful in wireline operations. The tool comprises a body having a first section and a second section. The first section defines an internal diameter that is larger than an internal diameter defined by the second section. A first turbine is disposed in the first section and a second turbine is disposed in the second section. The tool further comprises means for determining a rotational velocity of the first turbine and the second turbine. In use, fluids flowing through the downhole tool cause one or both of the turbines to rotate. By measuring the rotational speed of one or both of the turbines, the flow rate of fluid passing through the tool can be determined. Preferably, the tool is oriented so that downhole fluids encounter the first section, which defines the larger internal diameter, first as the fluids pass through the tool. The downhole tool is particularly well suited for use in shallow gas/coal bed methane reservoirs.

FIGS. 1-6 depict illustrative embodiments of a downhole tool 101 for measuring the flow of fluids in a downhole well environment, as is discussed in greater detail herein. Referring to FIG. 1, which is a side, elevational view of downhole tool 101, fluids enter a housing 103 of downhole tool 101 through an inlet end 105 and exit housing 103 through ports 107 defined by an outlet end 109. Outlet end 109 is configured to be connected to a downhole production string, a wireline, or the like. Housing 103 is configured for the attachment of a swab cup 111, shown in phantom, for channeling the flow of downhole fluids into inlet end 105 of housing 103.

FIG. 2 is a top, plan view of downhole tool 101. Housing 103 defines a passageway 201 therethrough, extending between inlet end 105 and outlet end 109. Disposed within passageway 201 are a first turbine 203 and a second turbine 205. One or both of turbines 203 and 205 are rotated by the fluid as the fluid flows through passageway 201, as indicated by an arrow 300 in FIG. 3. As best shown in FIGS. 3 and 4, housing 103 comprises a first section 301 and a second section 303. Passageway 201 extends through and is partially defined by first section 301 and second section 303. First section 301 exhibits a diameter D₁, while second section 303 exhibits a diameter D₂, which is smaller than diameter D₁. First turbine 203 is disposed in first section 301 of housing 103 and second turbine 205 is disposed in second section 303 of housing 103. In a preferred embodiment, first turbine 203 and second turbine 205 rotate about a common axis 305.

FIGS. 5 and 6 depict enlarged cross-sectional views, corresponding to and as indicated in FIG. 4, of first turbine 203 and second turbine 205. Referring to the embodiment shown in FIG. 5, first turbine 203 is rotationally affixed to a first bracket 501 via a first shaft 503. In one embodiment, first shaft 503 is rigidly affixed to first bracket 501 and first turbine 203 is free to rotate about first shaft 503. In an alternative embodiment, first turbine 203 is rigidly affixed to first shaft 503 and first shaft 503 is free to rotate, along with first turbine 203, with respect to first bracket 501. First bracket 501 is rigidly affixed to first section 301 of housing 103.

Referring now to the embodiment shown in FIG. 6, second turbine 205 is rotationally affixed to a second bracket 601 via a second shaft 603. In one embodiment, second shaft 603 is rigidly affixed to second bracket 601 and second turbine 205 is free to rotate about second shaft 603. In an alternative embodiment, second turbine 205 is rigidly affixed to second shaft 603 and second shaft 603 is free to rotate, along with second turbine 205, with respect to second bracket 601. Second bracket 601 is rigidly affixed to second section 303 of housing 103.

Each of first turbine 203 and second turbine 205 are operably associated with a means for measuring the speed at which the turbine with which it is operably associated rotates. In other words, first turbine 203 is operably associated with a first means for measuring the speed at which first turbine 203 rotates and second turbine 205 is operably associated with a second means for measuring the speed at which second turbine 205 rotates. The present invention contemplates many different configurations of the means for measuring the speed at which a turbine, e.g., turbines 203 and 205, rotate.

For example, as shown in FIG. 7, first turbine 203 is operably associated with a tachometer 701. In such a configuration, first turbine 203 is mechanically affixed to first shaft 503 and first shaft 503 rotates along with first turbine 203 with respect to first bracket 501. In one embodiment, tachometer 701 is mechanically coupled with first shaft 503. Alternatively, tachometer 701 may be in a non-contact relationship with first shaft 503 yet measure the rotation of first shaft 503 and, thus, first turbine 203. Electrical signals from tachometer 701 are transmitted via any suitable means, such as by a lead 703 or by wireless means. It should be noted that second turbine 205 may be operably associated with a tachometer, such as tachometer 701, as discussed herein concerning first turbine 203.

In another configuration, shown in FIG. 8, first turbine 203 is operably associated with a non-contact proximity sensor 801. In this embodiment, sensor 801 senses blades 207 (only one indicated in FIG. 2 for clarity) as blades 207 pass by sensor 801. The number of blades 207 sensed per unit of time is used to determine the rotational speed of first turbine 203. Electrical signals from sensor 801 are transmitted via any suitable means, such as by a lead 803 or by wireless means. It should be noted that second turbine 205 may be operably associated with a non-contact proximity sensor, such as non-contact proximity sensor 801, as discussed herein concerning first turbine 203, so that the sensor senses blades 209 (only one indicated in FIG. 2 for clarity) as blades 209 pass by the sensor.

It should also be noted that tachometer 701, shown in FIG. 7, and non-contact proximity sensor 801, shown in FIG. 8, are but two examples of the means for measuring the speed at which a turbine, such as turbines 203 and 205, rotates contemplated by the present invention.

As noted herein in reference to FIG. 2, first turbine 203 is disposed in a first section 301 of housing 103 and second turbine 205 is disposed in a second section 303 of housing 103. First section 301 exhibits diameter D₁, which is larger than diameter D₂ of second section 303. Due to the differences in diameters D₁ and D₂, turbines 203 and 205 will rotate at different, independent velocities for a given flow rate of fluid traversing passageway 201.

Downhole tool 101 is particularly useful in the measurement of flow rates of fluids in downhole well environments. For example, FIG. 9 depicts one illustrative well completion in which downhole tool 101 is implemented. In the illustrated implementation, downhole tool 101 is coupled with a production string or wireline 901, which extends to a wellhead 903. Production string or wireline 901 and downhole tool 101 are disposed in a horizontal or directionally-drilled well 905 that extends into a productive zone 907. Swab cup 111, shown in phantom in FIG. 1, generally seals an annulus between downhole tool 101 and well 905, such that fluids produced from productive zone 907 flow through passageway 201 (shown in FIGS. 2-8) of downhole tool 101, through production string 901 or around wireline 901, to wellhead 903.

In another exemplary well completion, shown in FIG. 10, downhole tool 101 is coupled with a production string or wireline 1001, which extends to a wellhead 1003. Production string or wireline 1001 and downhole tool 101 are disposed in a vertical well 1005 that extends into a productive zone 1007, production string or wireline 1001 allowing downhole tool 101 to move past a number of producing horizons. Swab cup 111, shown in phantom in FIG. 1, generally seals an annulus between downhole tool 101 and vertical well 1005, such that fluids produced from productive zone 1007 flow through passageway 201 (shown in FIGS. 2-8) of downhole tool 101, through production string 1001 or around wireline 1001, to wellhead 1003.

Downhole tool 101 provides significant advantages in the logging of fluids produced from productive zones, such as productive zones 907 and 1007, of wells, such as wells 905 and 1005. Such fluids may be gaseous in nature, such as methane, or liquid in nature, such as oil or water. In implementations wherein the flow of fluid is low, the flow may be insufficient to adequately rotate first turbine 203. In such situations, second turbine 205 will be adequately rotated by the fluid, as diameter D₂ of second section 303 is smaller than diameter D₁ of first section 301. Conversely, in implementations wherein the flow of fluid is high, first turbine 203 may rotate at a more appropriate speed for measuring the flow rate of fluid through downhole tool 101 than second turbine 205, as diameter D₁ of first section 301 is larger than diameter D₂ of second section 303. In implementations wherein the flow rate of fluid through downhole tool 101 rotates both turbines 203 and 205 at appropriate speeds, measurements can be taken using both turbines 203 and 205 to better characterize the flow rate of fluid through downhole tool 101. Note that the relationship between diameters D₁ and D₂ is implementation specific. All suitable relationships between diameters D₁ and D₂ are contemplated by the present invention.

It should be noted that the particular configuration of downhole tool 101 depicted in the drawings is merely exemplary of the many configurations contemplated by the present invention.

The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope of the invention. Accordingly, the protection sought herein is as set forth in the claims below. Although the present invention is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications. 

1. A downhole tool, comprising: a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter; a first turbine disposed in the first diameter of the housing; means for measuring a rotational velocity of the first turbine; a second turbine disposed in the second diameter of the housing; and means for measuring a rotational velocity of the second turbine.
 2. The downhole tool of claim 1, wherein the first turbine and the second turbine rotate about a common axis.
 3. The downhole tool of claim 1, further comprising: a bracket affixed to the housing; and a shaft coupled with the bracket and coupled with one of the first turbine and the second turbine.
 4. The downhole tool of claim 3, wherein the shaft is fixedly coupled with the bracket and the one of the first turbine and the second turbine is rotatably coupled with the shaft.
 5. The downhole tool of claim 3, wherein the shaft is rotatably coupled with the bracket and the one of the first turbine and the second turbine is fixedly coupled with the shaft.
 6. The downhole tool of claim 3, wherein the bracket is affixed to the housing within the first diameter of the housing and the first turbine is coupled with the shaft.
 7. The downhole tool of claim 3, wherein the bracket is affixed to the housing within the second diameter of the housing and the second turbine is coupled with the shaft.
 8. The downhole tool of claim 1, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a tachometer.
 9. The downhole tool of claim 1, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a non-contact proximity sensor.
 10. A downhole tool, comprising: a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter; a first bracket disposed in the passageway and affixed to the housing within the first diameter; a first shaft coupled with the first bracket; a first turbine coupled with the first shaft; a second bracket disposed in the passageway and affixed to the housing within the second diameter; a second shaft coupled with the second bracket; a second turbine coupled with the second shaft; means for measuring a rotational velocity of the first turbine; and means for measuring a rotational velocity of the second turbine; and wherein the first turbine and the second turbine rotate about a common axis.
 11. The downhole tool of claim 10, wherein the first shaft is fixedly coupled with the first bracket and the first turbine is rotatably coupled with the first shaft.
 12. The downhole tool of claim 10, wherein the second shaft is fixedly coupled with the second bracket and the second turbine is rotatably coupled with the second shaft.
 13. The downhole tool of claim 10, wherein the first shaft is rotatably coupled with the first bracket and the first turbine is fixedly coupled with the first shaft.
 14. The downhole tool of claim 10, wherein the second shaft is rotatably coupled with the second bracket and the second turbine is fixedly coupled with the second shaft.
 15. The downhole tool of claim 10, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a tachometer.
 16. The downhole tool of claim 10, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a non-contact proximity sensor.
 17. A well completion, comprising: a well extending to a productive zone; a wellhead; a downhole tool disposed in the well proximate the productive zone, comprising: a housing defining a passageway therethrough exhibiting a first diameter and a second diameter that is smaller than the first diameter; a first turbine disposed in the first diameter of the housing; means for measuring a rotational velocity of the first turbine; a second turbine disposed in the second diameter of the housing; and means for measuring a rotational velocity of the second turbine; and a production string disposed in the well and extending between and in fluid communication with the downhole tool and the wellhead.
 18. The well completion of claim 17, wherein the first turbine and the second turbine rotate about a common axis.
 19. The well completion of claim 17, further comprising: a bracket affixed to the housing; and a shaft coupled with the bracket and coupled with one of the first turbine and the second turbine.
 20. The well completion of claim 19, wherein the shaft is fixedly coupled with the bracket and the one of the first turbine and the second turbine is rotatably coupled with the shaft.
 21. The well completion of claim 19, wherein the shaft is rotatably coupled with the bracket and the one of the first turbine and the second turbine is fixedly coupled with the shaft.
 22. The well completion of claim 19, wherein the bracket is affixed to the housing within the first diameter of the housing and the first turbine is coupled with the shaft.
 23. The well completion of claim 19, wherein the bracket is affixed to the housing within the second diameter of the housing and the second turbine is coupled with the shaft.
 24. The well completion of claim 17, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a tachometer.
 25. The well completion of claim 17, wherein at least one of the means for measuring a rotational velocity of the first turbine and the means for measuring a rotational velocity of the second turbine comprises a non-contact proximity sensor. 